I was once in a unix shell thingy and it had gopher internet. It said it was the underground internet. Had a few things like BB and ftp, really nifty. I do recall my IBM Aptiva had a tool which could connect into gopher. What is it exactly?

Gopher was a sort-of predecessor to the World Wide Web. It provided information in a similar way (through linked documents and indices).

Wikipedia article describing it in detail